I have just noticed this over the last couple of days. I would get Ads popping up from Chitika that just happened to be the last thing that I searched for on google. OK fine must be some cookie it is reading. Then I started to get adsense doing the same thing. I finally noticed the words have been left in the top right search box of firefox. It does not do it each time but enough for me to worry. I have adsense on my site so I put some sex words in there did a search then went to my site. For some reason none of my adsense showed up. I reloaded the page and got some generic ads. I wonder if I leave enough bad word in the box I will be ad free.